Project Summary Ion channels are well recognized as important therapeutic targets because they play a crucial role in controlling a very wide spectrum of physiological processes. Human genetic studies identified a number of mutations in the renal ion channels leading to renal pathophysiology and abnormal changes in blood pressure. Understanding the basic mechanisms of ion channel regulation in the kidney and how alterations of such regulatory networks lead to water and electrolyte imbalance is fundamentally important for understanding of the development of hypertension and designing new strategies for treating this devastating and costly disease. The PI's research group has made key contributions in revealing specific mechanisms controlling several ion channels in the kidney and their contribution to the development of hypertension. Given the strong historical precedent that exists for discovering and commercializing successful drugs that modulate the activity of sodium, calcium, or potassium channels, and considering the critical role of renal ion channels in the control of blood pressure, new generations of therapeutic agents are expected to result from targeting ion channels in the kidney. The central tenet of this proposal is that several types of transporters, specifically ENaC, Kcnj10/Kcn16, Trpc6, and Clcn6, work either individually or in complex, interdependent combinations to delicately modulate the pressure natriuresis relationship and control blood pressure, respectively. The channels listed above were selected because either human mutations were reported in genes encoding these channels, or they were identified by Genome Wide Association Studies as genes associated with blood pressure control. Genomic modulation of channels and their regulators will be performed in the Dahl Salt- Sensitive (SS) rat, a well characterized and established model, which shares many features with salt-sensitive hypertension in humans. SS rat has been an enormously useful model as it is naturally occurring and recapitulates the major phenotypes found in hypertensive African Americans. Importantly, the SS model has been amenable to robust, cutting-edge genetic approaches to successfully create multiple mutant models, which will be used in this study. Considering the availability of these unique genetic rat models and novel approaches developed in my laboratory, I will be able to systematically study critical changes in corresponding ion transport mechanisms and downstream signaling pathways in the setting of salt-induced hypertension. The overall goal of this R35 proposal is to understand the impact of specific human gene variations on ion channel function and contribute to our understanding of the role of renal ion channels in normal and pathophysiological control of blood pressure.